1. Field of the Invention
This invention relates to improvements in taconite pellets and to the processing of taconite iron ore into taconite pellets. In particular, the invention relates to an improved binding material for taconite pellets.
2. Description of the Prior Art
Taconite pellets and the production of taconite pellets have been well known for many years. Taconite pellets are currently the most widely used feed material for use in blast furnaces for the production of iron and steel. The major reasons for using taconite pellets for iron and steel production is to simplify handling, shipping and other operations to which the taconite ore is subjected, since the taconite ore is typically mined a great distance from the blast furnaces. Taconite pellets are considered superior to other processed iron ore material for feed into a blast furnace.
Taconite ore is a relatively low grade of iron ore found in the region of Lake Superior as a hard rock formation. Taconite ore contains approximately 50% silica and approximately 18-27% iron.
Many materials have been used as binders for making taconite pellets. Some of the binders include: Bentonite (Auer et al, "Bentonite Update: Production, Reserves, Quality Control, and Testing," Society of Mining Engineering, pp. 1467-1473 (October 1979)), peat moss (Anthes et al U.S. Pat. No. 3,326,668), organic binders such as carbon hydrate, carbohydrates, dextrin, starches (Schierloh et al U.S. Pat. No. 3,765,869), tree bark (Ladell U.S. Pat. No. 3,811,865), carbonaceous material such as pitch-coal tar (Rueckl U.S. Pat. No. 3,212,877) or petroleum and high volatile coal, a clay having a 10-20% by weight content of residual coal (Endell U.S. Pat. No. 3,525,784), Portland cement together with flue dust or sludge and a water solution as an adhesive binding agent such as molasses or silicate of soda (Holz U.S. Pat. No. 2,417,493), a form of clay which contains 10-20% by weight of residual coal, sawdust, straw, polymers and others (Anthes et al U.S. Pat. No. 3,326,668). Presently, Bentonite is the most popular material used as a binder in taconite pellets.
The trend in pelletizing taconite is further described in a paper entitled "Direction of Pelletizing in the 80's," which was submitted at the 111th Annual Meeting of SME-AIME by J. H. Scheel and R. G. Lyons at Dallas, Tex. on Feb. 16, 1982.